import 'package:flutter/material.dart';

class Router extends StatelessWidget {
  @override
    Widget build(BuildContext context) {
      // TODO: implement build
      return MaterialApp(
        initialRoute: '/',
        routes: {
          '/': (BuildContext context) => MyHomePage(),
          '/signup': (BuildContext context) => SignUpPage(),
        },
      );
    }
}

class SignUpPage extends StatelessWidget {
  @override
    Widget build(BuildContext context) {
      // TODO: implement build
      return Navigator(
        initialRoute: 'signup/personal_info',
        onGenerateRoute: (RouteSettings settings) {
          WidgetBuilder builder;
          switch (settings.name) {
            case 'signup/personal_info':
              // Assume CollectPersonalInfoPage collects personal info and then
              // navigates to 'signup/choose_credentials'.
              // builder = (BuildContext _) => CollectPersonalInfoPage();
              break;
            case 'signup/choose_credentials':
              // Assume ChooseCredentialsPage collects new credentials and then
              // invokes 'onSignupComplete()'.
              // builder = (BuildContext _) => ChooseCredentialsPage(
              //   onSignupComplete: () {
              //     // Referencing Navigator.of(context) from here refers to the
              //     // top level Navigator because SignUpPage is above the
              //     // nested Navigator that it created. Therefore, this pop()
              //     // will pop the entire "sign up" journey and return to the
              //     // "/" route, AKA HomePage.
              //     Navigator.of(context).pop();
              //   },
              // );
              break;
            default:
              throw Exception('Invalid route: ${settings.name}');
          }
          return MaterialPageRoute(builder: builder, settings: settings);
        },
      );
    }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => new _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return new Scaffold(
      appBar: new AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: new Text(widget.title),
      ),
      body: new Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: new Column(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug paint" (press "p" in the console where you ran
          // "flutter run", or select "Toggle Debug Paint" from the Flutter tool
          // window in IntelliJ) to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              'You have pushed the button this many times:',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}
